Cyclomaltodextrin glucanotransferase (E.C. 2.4.1.19), also designated cyclodextrin glucanotransferase or cyclodextrin glycosyltransferase, in the following termed CGTase, catalyses the conversion of starch and similar substrates into cyclomaltodextrins via an intramolecular transglycosylation reaction, thereby forming cyclomaltodextrins, in the following termed cyclodextrins (or CD), of various sizes. Commercially most important are cyclodextrins of 6, 7 and 8 glucose units, which are termed alpha-, beta- and gamma-cyclodextrins, respectively. Commercially less important are cyclodextrins of 9, 10, and 11 glucose units, which are termed delta-, epsilon- and zeta-cyclodextrins, respectively.
Cyclodextrins are thus cyclic glucose oligomers (typically having a from 6 to 11 glucose units) with a hydrophobic internal cavity. They are able to form inclusion complexes with many small hydrophobic molecules in aqueous solutions, resulting in changes in physical properties, e.g. increased solubility and stability and decreased chemical reactivity and volatility. Cyclodextrins find applications particularly in the food, cosmetic, chemical and pharmaceutical industries.
Most CGTases have both starch-degrading activity and transglycosylation activity. Although some CGTases produce mainly alpha-cyclodextrins and some CGTases produce mainly beta-cyclodextrins, CGTases usually form a mixture of alpha-, beta- and gamma-cyclodextrins. Selective precipitation steps with organic solvents may be used for the isolation of separate alpha-, beta- and gamma-cyclodextrins.
Several amino acid sequences encoding peptides showing CGTase activity are known, such as sequences from Bacillus spp. (DE4009822) and Bacillus sterrothermophilius (EMBL entry no. U83799).
The object of the present invention is to provide novel CGTases, in particular CGTases which are useful in cleaning and detergent composition.
This object is met by the present invention as it has been found that CGTases according to the invention surprisingly exhibit good performance in starch removal when tested under realistic wash conditions.